Spinning process



Jan. 2, 1945. I I v MEHLER, JR 2,366,278

SPINNING PROCESS Filed Dec. 8, 1943 Albert JOJ'BP]? M6hl8I,JI. INVENTOR.

AT 0mm Patented Jan. 2, 1945 UNITED STATES PATENT hQFFICEe 2,366,278 SPINNING PROCESS Albert J. Mehler, Jr., Waynesboro, Va., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application December 8, 1943, Serial No. 513,342

' 2; Claims. (01. 18-54) This invention relates to the manufacture of crinkled filaments and yarns comprised of organic, solvent-soluble, thermoplastic substances.

- producing continuous, highly-though generally irregularly-crinkled, thermoplastic filaments by dry spinning a solution of filament-forming material at high jet velocities and without tension. Highly prinkled textile filaments are desirable because they give warmth, bulk and covering power to yarns, comprised of the same. Prior to Hitt, filaments formed by the dry spinning tech- 25 nique had been straight and, if crinkled filaments were desired, the crinkle was imposed in the ills.- ments after they had been formed. Crimping or crinkling subsequent to ,filament formationv has generally been brought about by mechanical treatment which is capable of producing only a few relatively large crimps per inch of filament length or by physical or chemical means, which treatment gives non-uniform results.

Unexpectedly, I have now found that filaments having,a relatively large number of evenly spaced crimps or crinkles per unit length can be formed in much the same fashion as is described in U; S. application Serial No. 477,012, provided certain critical conditions, hereinafter specified, are observed.

Therefore, the objects above stated are accomtion of solvent has established the following facts. If the jet velocltyis below about 200 yards per minute, straight, un crinkled filaments will be produced. Moreover. even through the solution is extruded at a very' high jet velocity, such as 800 yards per minute or more, and the yarn wound up under little or no tension, if the solution temperature at the time of extrusion is above 60 C., filaments having irregular crinkle or crinkles interspersed with nubs or twisted loops or entanglements will be produced. If the concentration of solids in the spinning solution is substantially below 30%, for example file.- ments having non-uniform crinkles, a coarse crinkle and/or a crinkle interspersed with nubs will invariably be produced under the conditions of free-fall spinning, regardless of the jet velocity-temperatu're relationship at jet velocities above 200 yards per minute.

A diagrammatic showing of one method oi carrying out this invention is given in the accompanying drawing. While the spinneret i may be mounted so as to extrude the solution in any direction fromyertically up to vertically down, that is, within the 180 angle on that side of the vertical towards the wlndup device, forpurposes Q oi illustration it is shown mounted in the horizontal position.

The filamentous streams 2 issuing from the spinneret should be allowed a free fall of at least.

two feet. While this f'reesfall may be as much as 10 to 20 feet or more, practical limitations suggest a free fall of from about 2 to 6 or 8 feet.

Whatever this distance is, the spinneret shouldbe so located that the filaments can fall freely without coming in contact with any support in -plishedby this'invention which, briefly stated.

com'prisesss'pinning a synthetic, solvent-soluble, organic, thermoplastic, filament-forming material dissolvedin one or-more volatile solvents,

said solution containing from .to by weight of solids, at a Jet velocity between 285 and 750 yards per minute. at a solution temperature of between 20 C. and 60 C.,and under such conditions that thefllaments issuing from the spiimeret fall freely two feet.- n

Mystudy tion of thermoplastic filaments by the evaporaio'r a distance of at least of the conditions affecting coagulatrates my invention.

their travel untilthey make contact with a suitable yarn guide, for instance the pigtail guide 8 shown (which should be mounted at a higher elevation than the minimum'elevation reached by the yarn therebefore) and, then wound up on a bobbin 4 at such a speed as is required by the rate of extrusion to maintain the desired freefall distance (about one-eighth the-jet velocity). -'I'he following specific example further illus- Example q A spin ning solution containing 32%of cellulose acetate (54.5% combined acetic acid) andhaving, a viscositywhen measured as a 24% solution in acetone of 350 pulses, and 1.5% methyl Cellosolve in acetone was extruded horizontally at a solution temperature of 30C. and with -a jet yelocity of 720 yards per minute through a 36- hole spinneret, each hole being 0.04 mm. in diameter. The filaments formed were permitted to fall freely a distance ofapproximately 3 feet before coming. under the influence of the draw of the windup bobbin to which the filament bundle was led through an intermediate pigtail guide and traverse guide positioned as shown in the drawlng.- The yarn collected was composed of filaments having a fine, regularly spaced crinkle (about 15 crimps per inch of filament length as collected); When subsequently twisted by any of the usual twisting methods to 2 or 3 turns per inch and suitably finished by the application of from 1% to 3% of oleaginou material, the yarn was found to have pleasing soft hand, good covering power and was well adapted for conversion into textile fabrics by the usual procedure.

- Because of the high jet velocities needed to pro-- duce the desired fine crlnkles and the relatively lowwindup speed needed to prevent positive drawing of the filaments from the spinneret, the individual filament deniers are, as a rule, fairly large, for example in the range of from 5 to 30. Under-the conditions of spinning mentioned in the example, the denier of individual filaments will be in the range of from to 15.

Although the. invention has been described specifically with reference to the spinning of aceascents The spinning solutions may contain, in addition to the filament-forming substance, a suitable modifying agent compatible therewith, for instance a plasticizer, a high-boiling solvent, or the like. Also, the solution may contain modifying agents, such as dyes, pigments, non-solvent diluents, and the like.

By means of the method of this invention it is possible to produce yarns comprised of synthetic,

thermoplastic, organic filaments which have a fine crinkle with the intensity varying from about 10 to 40 crimps per inch, which crimps are reasonably uniform in intensity and spacing and are in the form of a helix; 1. e., the crinkle is symmetrical at all points around the yarn axis; which yarns are eminently suited for the production of wool-like fabrics. While the filament deniers are somewhat larger than are customarily produced in the form of straight filament yarn, by decreastone-soluble cellulose acetate, it is applicable to the spinning of any thermoplastic, filamentforming substance soluble in organic solvents,

such as other cellulose acetate, cellulose propionate, cellulose butyrate, cellulose aceto-propio nate, cellulose aceto-butyrate or the like; organic solvent-soluble cellulose ethers, such as methyl cellulose, ethyl cellulose, benzyl cellulose or, the like; mixed celluose ether-esters, such as methyl cellulose acetate, ethyl cellulose propionate, etc.; vinyl polymers, such as vinyl esters, for example vinyl acetate; vinyl ethers, suchas vinyl acetal; copolymers of vinyl chloride and'vinyl acetate, such as .Vinylite' V"; copolymers of vinylidene chloride and vinyl chloride, such as "Saran; polystyrene; nylon; methacrylate polymers, and the like. Any suitable organic solvent or combination of solvents may be used depending, of

, course, upon the specific thermoplastic materials being spu the filament-forming material is cellulose-acetate.

ing the spinneret hole size, filament deniers as low as 5 can be produced. v

Since it is obvious that many changes and modifications may be made in the process and products set forth in the description without departing from the spirit and scope of the invention, it is understood that. the invention is not to be limited thereto except as defined in the appended claims.

I claim: 1. The process which comprises spinning a synthetic, organic, thermoplastic, filamentforming material from a solution thereof in a-volatile solvent through a spinneret, said solution containing from 30% to 40% by weight of solids, into an evaporative atmosphere, at a Jet velocity of from 285 to 750 yards per minute, and at a solution temperature of from 20 C. to C. whereby to form filamentous streams and permitting said filamentous streams to fall freely in said'evaporative atmosphere for a distance of at least 2 feet from the spinneret, whereby to form continuous filaments having fine and uniformly spaced crinkles.

2. The process according to claim 1 wherein ALBERT J. MEHLER, JR. 

